A hydrogen peroxide-containing liquid oxygen-type bleaching agent is a product highly accepted by the consumer because it is usable for colored clothes having a design and applicable directly to dirt. However, the liquid oxygen-type bleaching agent is inferior in oxidizing power to a chlorine-type bleaching agent and thus has a problem of weak bleaching power. For the purpose of increasing the bleaching power of the oxygen-type bleaching agent, an oxygen-type bleaching agent further containing a bleaching activator of an organic peracid precursor type, which has a higher oxidizing power than hydrogen peroxide, has been utilized in the field of detergents for clothing in recent years. This bleaching activator of an organic peracid precursor type reacts with hydrogen peroxide in a weakly alkaline washing bath, to form an organic peracid. By the oxidizing power of this formed organic peracid, a bleaching effect is obtained. Generally, the bleaching activator has an active ester group etc., and thus attention should be paid to the storage stability thereof in the form of a product. A powdery oxygen-type bleaching agent is made stable by separating a granulated product of a bleaching activator as other particles from sodium percarbonate serving as a source of hydrogen peroxide. In a liquid oxygen-type bleaching agent, on the other hand, hydrogen peroxide and the bleaching activator cannot be separated from each other in the liquid, and thus the hydrolysis of the bleaching activator by hydrogen peroxide is hardly suppressed, and stable blending with the bleaching activator is extremely difficult.
Hydrogen peroxide and a bleaching activator exhibit a higher bleaching effect in the neutral to alkaline range than in the acidic range, but hydrogen peroxide and a bleaching activator are poor in storage stability in the neutral to alkaline range. Accordingly, there is need for techniques wherein a liquid oxygen-type bleaching agent containing hydrogen peroxide and a bleaching activator is stabilized at a higher pH to attain excellent bleaching performance. As a method conceivable for achieving this object, there is an embodiment wherein two preparations, that is, a low-pH composition containing a bleaching base and a high-pH composition containing an alkali, are prepared in separated forms and mixed at the time of use to form a bleaching composition, but a preparation of a one-pack liquid type is desirable from the viewpoint of simplification of a container and usability.
JP-B 2669590 discloses a liquid bleaching composition formulated stably by forming mixed micelles by using a bleaching activator and a highly interactive surfactant simultaneously.
JP-A 10-72595 discloses a liquid bleaching composition excellent in storage stability over a long time and exhibits bleaching performance even when used alone by applying a pH jumping technique using a boron compound and a polyol compound simultaneously (technique using a system wherein upon dilution, pH is increased beyond neutrality (pH 7)).
An oxygen-type liquid bleaching agent based on hydrogen peroxide became widespread because it scarcely damages dye/fibrous material and can be easily used by direct application to the stain. Autolysis of hydrogen peroxide proceeds at the weakly alkaline range to generate an oxygen gas, and the pH of the oxygen-type liquid bleaching agent marketed presently is regulated in the acidic range. However, the bleaching effect of hydrogen peroxide is higher in the neutral to alkaline range than in the acidic range, so there is a need for techniques of stabilizing hydrogen peroxide at a higher pH.
JP-A 11-181491 and JP-A 11-181492 disclose a liquid bleaching composition wherein hydrogen peroxide is stabilized in a high pH range (pH 4 to 7) by a phenol derivative.
Studies on incorporation of functional base materials such as a bleaching activator, a perfume and a dye into the product blended with hydrogen peroxide have been conducted for the purpose of improving bleaching performance and popularity, but these base materials have a structure such as an ester group, an unsaturated bond etc., and are easily denatured and inactivated by hydrogen peroxide, and thus stabilization thereof is difficult, and in the related art, there is a problem of storage stability over a long period.
The bleaching activator reacts with hydrogen peroxide in a washing bath to form an organic peracid which in turn effectively decomposes stain and dirt thereby improving the bleaching power and assisting with solving the problem of the oxygen-type bleaching agent. The bleaching activator used in recent years includes tetraacetylethylenediamine (TAED), sodium nonanoyloxybenzenesulfonate. These compounds have structures such as an unstable ester group and amide group and thus undergo hydrolysis and peroxide hydrolysis in an aqueous hydrogen peroxide solution at pH 3 or more, so there is a problem of easy inactivation.
JP-A 6-207196 discloses techniques of using suppression, in surfactant micelles, of hydrolysis of an ester linkage. JP-A 11-50099 discloses a bleaching composition having excellent storage stability and bleaching performance by using a hydrophobic bleaching activator blended with a fatty acid or a salt thereof.
In the field of detergents, softeners etc., an interest in the odor of a bleaching agent becomes higher than before in recently attracted product development of a perfume for a preferred odor and for affectivity performance. However, the perfume also has a structure such as an unsaturated bond and aldehyde group which is highly sensitive to oxidation, and is very unstable in the presence of hydrogen peroxide.
For improving the odor stability of the perfume, JP-A 11-50099 discloses a composition containing a perfume of a specific odor and a specific aromatic compound incorporated therein. JP-A 2002-338997 discloses a method of improving perfume stability under exposure to light, referring to incorporation of a phenol compound and a chelating agent.
The dye has an effect not only of improving an liking to a liquid composition by coloration thereof but also of improving convenience by coloring a liquid composition to facilitate visualization thereof in fluid measurement and visualization of the place where the liquid composition was applied to staining. The coloration of a bleaching agent has been examined from long ago, but the dye has a structure highly sensitive to oxidation, such as a conjugated structure or a chromophore, and thus prevention of the dye from fading in hydrogen peroxide has been insufficient.
JP-B 2688844 discloses a composition containing a nonionic surfactant and an acidic dye. JP-A 2003-268398 discloses a method wherein storage stability under conditions including those under light exposure is improved by incorporating a phenol-type radical trapping agent. JP-A 5-271691 discloses a liquid bleaching composition having excellent storage stability, containing a florescent brightener as one kind of dye dispersed in a bleaching agent.